Pro: Supports the SATA port multiplier feature necessary for connecting multiple SATA devices to a single SATA port (e.g., through a multi-disk external enclosure). I've only tested the eSATA port, but I don't see why the internal one would be any different.
Con: The full size bracket is a poor fit. It's a bit of a squeeze to get the card into a PCI-E slot because the bracket gets in the way. The bracket is also a bit too long, so you can't quite screw it in place securely. I don't know if the included low profile bracket is a better fit because I haven't got a compact case to try it on.